This application claims priority to Japanese Application No. Hei 11-274569, filed Sep. 28, 1999.
1. Field of the Invention
The present invention relates to a small watercraft, and more particularly to a system for deterring water invasion through the exhaust system of a watercraft.
2. Description of Related Art
Personal watercraft have become very popular in recent years. This type of watercraft is quite sporting in nature and carries a rider and possibly one, two or three passengers. A relatively small hull of the personal watercraft commonly defines a riders""area above an engine compartment. An internal combustion engine frequently powers a jet propulsion unit which propels the watercraft. The engine lies within the engine compartment in front of a tunnel formed on the underside of the watercraft hull. The jet propulsion unit is located within the tunnel and is driven by a drive shaft. The drive shaft usually extends between the engine and the jet propulsion device, through a wall of the hull tunnel.
As is typical with marine propulsion systems, the engine exhaust gases are discharged to the atmosphere either at, below or close to the water level at which the watercraft is operating. Thus, care must be taken to ensure that water cannot enter the engine through the exhaust system. This problem is particularly acute in personal watercraft. Because of their sporting nature and high degree of maneuverability, personal watercraft can be expected to be capsized occasionally. When capsized and subsequently righted, water occasionally may flow through the exhaust system and into the engine, possibly causing serious damage to important engine and exhaust system components.
Accordingly, a need exists for a watercraft exhaust system that discharges exhaust gases at, below or close to the water level at which the watercraft is operating and which prevents invasion of water into the engine through the exhaust system.
In accordance with one aspect, a watercraft is provided that has a hull defining an engine compartment. An internal combustion engine is located within the engine compartment and has an output shaft. A propulsion device is carried by the hull and is connected to the engine output shaft. An exhaust system delivers exhaust gases from the engine to the environment. The exhaust system includes an exhaust expansion chamber, a connecting pipe communicating with the expansion chamber, and a water trap device communicating with the connecting pipe. The water trap device has a discharge tube formed in an upper portion thereof. A downstream end of the connecting pipe opens within a rearward portion of the water trap so that the connecting pipe downstream end is positioned outwardly from a center line of the watercraft relative to the discharge tube.
Further aspects, features, and advantages of the present invention will become apparent from the detailed description of the preferred embodiment which follows.